You get 720p which is 720 x 1280 the p stands for progressive the frame rate can vary from 24,25,50, or even 60 frames per second
You also get 1080i which is 1920 x 1080 the I stands for interlaced the frame rate is 24,25 frames or 30 frames and can go up to 60
With 25 frame interlaced you get 50 fields either top or bottom first together making up 25 frames
Don’t be fooled by the big numbers 720p has nearly the same resolution as 1080i
50i has the same frame rate as 25p with 50 half frames or fields combined to make up 25 frames
Many professional video editors work in 720p because it is better to edit in and resize is better with no line blending when resampling
Also masking is more accurate and so is chroma keying